Evaluating Software Architectures: Methods and Case Studies Chapter 1. What is a Software Architectures?

1
Evaluating Software Architectures Methods and
Case StudiesChapter 1. What is a Software
Architectures?

• 14 December, 2002
• Cho, N. K.

2
1? ????? ????? ?????

• ??? ?, ??, ???? ???? ?? ?? ??? ???. ???
  ??(Construction)??. ??? ?? ??? ? ??? ????, ??
  ?????. ? ?? ??? ?? ??? ???. ? ????!.
  ????(Architecture)?? ?? ???.
• - ? ?????, 1923
• Architecture From Prehistory to
  Post-Modernism?? ??

3
????? ???? ??? ??

• ?????(Edsgar W. Dijkstra, ??? http//c2.com/cgi/wi
  ki?PronouncingDutch)
• 1960?? ???? ??? ??? 2002? 8? ???
  ??(http//www.cs.utexas.edu/users/EWD/)???? ?
  50??? ??? ???(http//www.cs.utexas.edu/users/EWD/i
  ndexEWDnums.html)? ??? ???? ??. ????? ????
  Dijkstra ?????? ?? ??????? ? ??? ??????, 50?? ?
  High level ????? ?? ALGOL? ?????. 1968? Go To
  Statement Considered Harmful(http//www.acm.org/cl
  assics/oct95/)?? ? ??? ???? ??? ?????(Structured
  Programming)? ??? ?????, DPP(Dining Philosophers
  Problem)? ???? ??? ????? ??? ?????? ????? ????
  ??? ??? ??. ??? ??(SoC)? ???(Abstraction)?? ?????
  ?? ??. ??? ???? 1972? ACM(Association for
  Computing Machinery) Turing Award(http//www.acm.o
  rg/awards/turing_citations/dijkstra.html) ??.
• ???(Frederick P. Brooks)
• 1964? ??? IBM360 ??? ???? ??? ???, ??? ??? ????
  1975? ??? The Mythical Man-Month Essays on
  Software Engineering? ??. ? ?? ? ??? ????? ??
  ????? ?? ?? ???? ????? ???? ??. ??? ????, ????,
  ??? ????? ??? ??? ??? ?? ??? 1999? Turing
  Award(http//www.acm.org/awards/turing_citations/b
  rooks.html) ??.
• ????(David L. Parnas)
• ????? ??? ???. 1972? ????? ?? On the Criteria To
  Be Used in Decomposing Systems into
  Modules(http//www.acm.org/classics/may96/)??
  modularization? ???. ?? ??(Information Hiding),
  ??? ??(Separation of Concerns)? ?? ???? ??? ??.
  ?? ??? 33?? ?? Software Fundamentals Collected
  Papers by David L. Parnas? ?? ??? ?????? ?? ????
  ???.

4
????? ????? ??

• ??????(stakeholder)?? ??? ???? ??.
• ???????? ??? ???? ??? ??? ??? ??? ??? ? ??.
• ????? ????? ????????? ????? ??, ??? ????, ??? ???
  ? ?? ??? ???? ???? ????.
• ???? ??? ??? ?? ??? ??? ?? ???.
• ? ?? ???? ??? ?? ??? ? ??? ??.
• ??? ??, ?????? ???, ?? ?? ??? ??? ?? ?? ???
  tradeoff? ????? ???.
• ?? ????? ??? ???? ? ?? ???? ??? ??(abstraction).
• ???? ??? ???? ??, ???? ???? ??? ???? ???? ???? ??
  ??.
• ? ??? ?? ??? ????? ???, ???? ??? ??? ? ?? ????
  ??.
• ?? ??? ?? ??(????)??, ??? ????? ?? ?? ?? ???? ??
  ???? ? ??.

5
????? ????? ??

• ???? ?? ??? ???? ????? ?????, ????? ????, ??
  ????? ???? ??, ??? ???? ??? ??? ??? ???? ???? ???
  ???.
• Bass, Clements, Kazman, 1998
• Software Architecture in Practice?? ??
• ????? ???? ????? ???? ???? ??. ????? interface?
  connector? ???.
• ????? ?? ???? ?????? ??? ??? ????? ??? ???? ?.
• ??? ?(view) ??? ???? ?? ??? ??? ?? ??.

6
1.1 ???????? ??? ???? ?????? ????

• ????? ????? ? ??? ???? ??? ????.
• ?? ??????? ?? ? ? ?? ???(lingua franca)? ??.
• ??????? ??? ??? ??? ???, ??? ???? ???? ?? ? ????
  ? ??? ??.
• ???, ???, ??, ???, ???, ???, ??? ??? ???? ????
  ??? ?? ??.
• ??, ??, ??? ??? ?? ???? ?? ???? ???(blue print)
  ??.

7
1.1.1 ???????? ????? ?? ??? ?? ?? ? ??

• ????? ???? ??? ??? ???????? ??? ???.
• ???(user)
• ??? ????, ??? ? ???, ??? ???? ???.
• ??(customer)
• ????? ??? ??? ?? ?? ??? ??? ? ???? ??? ???.
• ???(manager)
• ??? ???? ???, ????? ??? ???? ???? ???? ??? ? ??
  ??? ???? ???? ??? ???.
• ???(developer)
• ? ?? ??? ?? ?? ????? ??? ???.
• ???(tester)
• ??? ???? ???? ??? ??? ????? ??? ??? ???.
• ??? ?? ???? ??.

8
1.1.2 Architectural Views (1/2)

• ?? ?? ?? ???
• ?, ????, ????, ??? ??? ?? ??? ??.
• ?? ???? ??? ?(view)? ??.
• ?? ?? ??? ???? ??? ?????.
• ???? ????, ??? ???? ??.
• ?, ? ????? ?? ?? ??? ??? ??? ?? ?? ????? ??.
• ???, ? ????? ??? ?? ???? ???, ?? ??? ??? ???? ??.
• ???? ??? ?? ?? ??? ?? ???, ??? ?? ???? ???? ???
  ???? ???, ?? ?????? ???? ??? ?? ???? ??.
• ?? ??? ????, ??? ???? ?? ??? ???? ?(architectural
  view)? ???(description)? ??(prescription)? ??? ??
  ??.

9
1.1.2 Architectural Views (2/2)

• ????? ???? ?? ??? ????
• Functional view (Logical view??? ??)
• Concurrency view (Process ?? Thread view)
• Code view
• Development view (Implementation view)
• Physical view (Deployment view? ?? ?? ??)
• 5?? ?? ??? ??? ? ??
• ? ?? ?? ??,
• ? ?? ???? ?? ????? ?? ??? ??,
• ?? ?? ?????,
• ? ?? ?? ??(?? ?? ??? ?? ??).

10
Functional View

• ??
• ??? ??(function)? ???? ??? ?? ??
• Component
• function, key system abstraction, domain element
• Relationship
• dependency, data flow
• ?? ???
• ??? ????, ?????? ???, ???
• ?? ??
• ???? ???? ?? ???? ??? ??? ?? ?.
• ????? ??? ???? ??? ??.
• functionality, variability of functionality,
  relationship among these functionalities.
• ??
• ?? 1.1

11
Concurrency view

• ??
• ???? ??? ??, ?? ???? ?? ???? ??? ???, ???? ???
  ????????, ??? ???? ???? ???? ?
• Component
• process, thread
• Relationship
• data flow, event, ????? ?? ???(synchronization on
  shared resources)
• ?? ???
• ??? ???, ???? ??? ???? ??? ?? ??, integrator,
  tester
• ?? ??
• ???? ?? ???? ??? ???? ??? ??? ????? ??? ????? ?
  ?.
• performance, availability, and deployment of
  system.
• ??
• ?? 1.2

12
Code view

• ??
• ?????? ???? ??? ?? ??
• Component
• class, object, procedure, function, ?? ???? ????
  ???(subsystem, layer, module)
• Relationship
• call, method invocation, ???? ?????
  ??(is-a-sub-module-of)
• ?? ???
• ?????, ???, ????
• ?? ??
• ???? ??? ??? ??? ????? ????? ? ?.
• modifiability/maintainability, portability, and
  subsetability.
• ??
• ?? 1.3

13
Development view

• ??
• code view? ?????, ????? ??? ??? ?
  ?????(repository)? ??? ?? ?
• Component
• ??, ????
• Relationship
• ?????(containment)
• ?? ???
• ????? maintainer, manager, ?????
• ?? ??
• ??? ??? ??? ???, ????? ?? ??? ??? ? ?.
• modifiability/maintainability.
• ??
• ?? 1.4

14
Physical view

• ??
• ???? ??? ???? ??? ????? ?? ?
• Component
• CPU, sensor, actuator, ???? ?
• Relationship
• ???, ?? ?????? ??(??, ??? ??)
• ?? ???
• ???? ? ??? ????
• ?? ??
• ??? ??, ?? ? ????? ?? ??.
• performance, availability, scalability, security.
• ??
• ?? 1.5

15
Summary of views

• ?? ????? ???? ???? ???? ??? ??? ? ?? ?????
  ????.
• ?, ?? ?? ???? ??? ? ??? ??.
• ?? ??? ??? ?? ?? ???? ??? ?? ??.
• ?) deployment view? ????(concurrency view)? ??
  ????(physical view)? ?? ??? ????.
• ???? ?? ??? ??? ???? ??? ??? ??? ?? ??, ??? ?? ??
  ???? ???? ?.
• ? ?? ???? ?
• Philippe Kruchten? ??? 41 View ??

16
1.1.3 ADLs(Architecture Description Languages)
(1/3)

• ??? ??? ????
• ?????? ?? ??? ???? ??? ?????,
• ??? ??? ???? ??? ??,
• ???? ??(architectural description)? ???? ??
  ???(blueprint)? ??? ??? ??.
• ???? ???(ADL)
• ????? ??? ???? ?? ????? ???? ?? ???? ????.
• ?? ??? ???? ????? ??(??)?? ?? ??? ??? ??/???? ??.
  ??? ??? ?????? ??(deadlock detection,
  consistency, completeness, real-time properties,
  ??)? ??? ?????.
• ???, ????? ?????? ?? ??? ?? ??.

17
1.1.3 ADLs(Architecture Description Languages)
(2/3)

• Wright
• CMU
• Allen Garlan, 1997
• provide a formalism that focuses on explicit
  connector types and analysis associated with
  architectural connection.
• Unicon
• CMU
• Shaw Garlan, 1996
• support style-based architectural construction by
  interconnecting predefined or user-defined
  architectural components.
• Rapide
• Standford
• Luckham et al., 1995
• provide an executable ADL based on a rule-event
  execution model for prototyping, simulating, and
  analyzing software systems.
• C2SADEL
• UC Irvine USC
• balances formality and simplicity
• describes C2 components internal object

18
1.1.3 ADLs(Architecture Description Languages)
(3/3)

• UML? ???? ???? ??? ? ???
• ????? UML? ???? ??/??? ??? ????, ???? ???? ????
  ?? ADL? ???.
• UML? ADL? ???? ?? ???
• ?? ???? ???(?? ??, layer)? ?? ???? ???.
• ????? ?????? ?? ?? ??? ???.
• ???? ???? ???, ????? ???? ??? ???? ???.
• UML ?? ????? ?? ????? ????? ??? ?? ??.
• UML 2.0? ???? ??? ??? ??.
• UML Profile for Architecture Definition

19
1.2 ?? ?? ?? ??? ??? ?? ?????? ???? (1/3)

• ????? ?? ?? ????(quality attribute)???? ??? ???,
  ??? ???.

20
1.2 ?? ?? ?? ??? ??? ?? ?????? ???? (2/3)

• ????? ?? ?? ??? ??? ???.
• ???? ??? ?? ??? ??? ?????? ??? ???? ?? ???, ????
  ??? ??? ??? ?? ???? ??? ??.
• ???? ??
• If you have four groups working on a compiler,
  you'll get a 4-pass compiler.
• ?????? ???? ????? ????? ??? ??? ?? ?????? ????
  ??? ?? ???, ?? ?? ?? ??? ???? ??? ??? ??????? ??
  ??. ???? ?? ??? ??? ??? ??? ???, ??? ?????? ?????
  ??? ?? ? ???.
• ?, ??? ?? ??(separation of concerns)? ?????? ???
  ??? ????.

21
1.2 ?? ?? ?? ??? ??? ?? ????? ???? (3/3)

• ????? ??? ?? ??? ?????? ????.
• .Net ???? ????? ????, CORBA? EJB ??? ????? ?????
  ???? ??? ? ??.

22
?? (1/2)

• ????? ????(Christoper Alexander)
• UC ??? ????, ????, ???, ????.
• ??? ?? ??? ???? Pattern Language? ?? ?.
• ??, Pattern Language? ??? ?? ???, ???, ????,
  ??() ? ??? ??? ??? ??.
• ??
• ???? ?? ???? ???? ???? ???? ?? ???? ???? ????
  ???. ?? ?? ??? ????? ? ?? ??? ???? ???? ? ??.
• ????? ????, 1977
• A Pattern Language?? ??

23
?? (2/2) Placing Window

• Problem
• Everybody loves window seats, bay windows, and
  big windows with low sills and comfortable chairs
  drawn up to them.
• Solution
• In every room where you spend any length of time
  during the day, make at least one window into a
  "window place."

• Stand in room and see where to put windows
• . . . . . . .
• Place openings
• Double check and adjust
• . . . . . . .
• Check from outside and adjust
• Place rough frames
• Make rough stub at fenestration pattern
• . . . . . . .

24
1.2.1 ???? ??? (1/3)

• ????? ???? ???? ??? ??? ?? ?? ????
  ???(architectural styles)
• ???? ??? ?? ?? ?? ?? ??? ????.
• ????
• ????? ???? ??? ?? ???? ?? ??? ??? ????? ???
  ?????, ?? ????? ????? ???? ??? ??.
• ????
• ??? ???? ??? ???? ??.
• ????? ????? ????.
• ?? ??? ?? ?? ???? ???? ?? ???.
• ???? ???? ??? ??? ??? ??.

25
1.2.1 ???? ??? (2/3)

• Shaw? Garlan? Software Architecture?? ???? ????
  ??? ?? ??? ?.
• Independent components
• communicating process, implicit invocation,
  explicit invocation
• Data flow
• batch sequential, pipe filter
• Data-centered
• repository, blackboard
• Virtual machine
• interpreter, rule-based
• Call/return
• main program subroutine, object-oriented,
  layered
• ??? ???? ???? ?? ????? ????? ????, ??? ?? ?? ??
  ???? ??? ?? ????? ??.

26
1.2.1 ???? ??? (3/3)

• ???? ???? ???? ??? ? ??
• Component type
• data repository, process, object
• Connector type/interaction mechanism
• subroutine call, event, pipe
• Topology
• star, ring, hierarchical
• Constraint on topology
• data repository ???? ??? ??? ?? ??? ??? ? ??.
• Benefit of style
• ???? ????? ??? ?? ???? ??? ?? ????? pipe filter
  ???? ????.

27
Pipe Filter ???

• Meaning
• ????? ???? ??? ?? ????, ? ??? ?? ????? ???? ????.
• Component
• Filters
• Connector
• Pipes
• Constraints
• ??? ?? ?????.
• ??? ?? ?? ??? ?/? ??? ?? ??? ??.
• Layout

Computation
Data flow
Input
Output
28
Layered ???

• Meaning
• ?????? ???? ??? ???, ? ???? ??? ???? ??? ?? ?????
  ??? ? ??.
• Component
• Layers
• Connector
• Protocols of layer interaction
• Constraints
• ??? ???? ????? ??? ??.
• Layout

Composite of various elements
Communication protocol
29
Shared repository ???

• Meaning
• ??? ?? ?????? ??? ? ?? ?????? ???, ?????? ???
  ???? ??? ??.
• Component
• Central data structure represent the current
  state
• A collection of independent components operate on
  central data store
• Connector
• transfer control and/or data
• Constraints
• ?? ?????? ??? ?? ??? ??? ???? ????.
• Layout

Computation
Memory
Data access
Blackboard (shared data)
30
Implicit invocation ???

• Meaning
• ???? ???? ??? ???, ???? ????.
• Component
• Component interfaces are methods and events
• Connector
• invocation is either explicit or implicit in
  response to events
• Constraints
• ???? ?? ???? ?? ??? ????? ??? ? ??? ??.
• Layout

Event
Announce
Trigger
31
???? ??? ??
32
1.3 ?? ????? ???? ? ?? ????? ????

• ????? (??? ??? ??? ???? ??? ???? ?? ??? ? ? ??)
  ???? ? ?? ????, ?? ??? ?? ?????(?? ??? ?????
  ????????? ??).
• Software Product Line? ????? ????? ? ?? ?????
  ???? ????? ????, ??? ????? ????? ?????? ??? ?????
  ?? ???? ???? ??? ???.

Essential technologies
pertain to
market strategy/ application domain
Domain Engineering
is satisfied by
Architecture
share an
architecture
Architecture based Development
Products
is used to structure
CORE ASSETS
are built from
components
Reengineering
33
1.4 ??

• ????? ???? ???? ?? ??? ????.
• ????? ???????? ???? ?????, ???, ???, ??, ??? ??
  ?? ?????? ? ? ?? ????.
• ????? ?? ?? ?? ??? ??? ?? ?????, ??? ???? ????
  ???? ?? ??? ?? ? ??? ????.
• ????? ???? ? ?? ????, ??? ????? ???? ??? ????
  ????? ??? ??.

34
1.5 ??? ?? (1/2)

• Software Architecture
• Dijkstra68, Parnas72 ?? ????? ??? ??
• Bass98, Hofmeister00, Shaw96, Bosch00,
  Malveau01 ??? ??
• Architectural view
• Kruchten98 RUP ??? 41 ?
• Bass98, Jazayeri00 ??
• Hofmeister00 ???
• Parnas74 ??
• Architectural style
• Bass98, Shaw96 - ??
• Buschmann96, Schmidt00 ????
• Gamma95 ??? ??
• Jacobson97 ???? ???? ?? ???? ???
• Smith01 ??? ??
• Software product line
• Clements01 ???
• Jacobson97 ?????? ???? ???? ??
• Bass98, Bosch00 ????? ??

35
1.5 ??? ?? (2/2)

• Business consideration
• Sullivan97 - ??
• Kazman01 ???? ????
• Conway68 ??? ?? ????? ??
• Architecture-based design
• Bachmann00 Architecture Driven Design Method
• Implementation conforms to the architecture
• Yeh97, Kazman99, Krikhaar99, Finnigan97
  reverse engineering
• ADLs
• Rational ???? UML? ???? ???? ????
• Medvidovic00 ADL ??
• Garlan97 - ACME

36
1.6 ?? ????

• ????? ?? ??? ????? ?? ??? ??? ????, ??? ??? ????
  ???? ?? ?? ?? ??? ?? ?? ?? ???
• ????? ????? ?? ??????? ????, ?? ?? ???
• ??? ??? ? ???? ?? ???? ???????? ????, ??? ?? ??
  ??? ?? ???
• deployment view? process view? ??? physical
  view?? ?? ?? ??? ??, ??? ?? ??? ??? ??? ??
• ?? ??? ??? ?? ??? ?? ?????
• layered architecture? ???? ??? ?? ?? ??? ????
• ???? ??? ??(data flow)? ???? ??? ?? ?? ??? ????

37
?? ???

• gtFrom Paul Clements ltclements_at_sei.cmu.edugt
• gtTo "cho namkyu" ltnamkyu_cho_at_hotmail.comgt
• gtCC kazman_at_sei.cmu.edu
• gtSubject Re Question in ESA.
• gtDate Fri, 13 Dec 2002 075904 -0600
• gt
• gtDear Namkyu Cho,
• gt
• gtATAM is two syllables
• gt"A" (rhymes with say, way, etc.) "TAM"
  (rhymes with dam)
• gt
• gtSAAM is one syllable that rhymes with dam.
• gt
• gtARID is two syllables.
• gt"AR" (like "air") "ID" (rhymes with bid)
• gt
• gtI visited Korea last year and learned that your
  language is
• gtmuch easier and has much better rules for
  pronouncing
• gtwords than ours. I can understand your
  difficulty, especially

gtAt 1217 PM 12/13/2002 0000, cho namkyu
wrote gtgtDear Dr. Paul Clements and Rick
Kazman gtgt gtgtLet's me introduce myself. I'm Namkyu
Cho, an independent gtgtconsultant. and I have
studied your book, "ESA" with my colleagues.
gtgtPronouncing English is not easy for us because
our native language gtgtis Korean. I've been
wondering how to pronounce the word, ATAM,
gtgtSAAM, and ARID? gtgt gtgtThank you for your
attention. gtgtBest Regards, gtgt gtgtNamkyu Cho